Ethereal-users: Re: [Ethereal-users] Ethereal Software

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From: Guy Harris <guy@xxxxxxxxxx>
Date: Tue, 12 Nov 2002 12:47:03 -0800
On Tue, Nov 12, 2002 at 02:17:10PM -0500, Aylsworth, Joshua H (TRANS) wrote:
> I am writing because I was referred to you when the task arose of how to
> obtain a bit error rate.

That was probably a mistake on the part of the person who referred you,
as Ethereal does its packet capturing above the network device driver,
and therefore does not get any error statistics from the network device
driver and thus cannot calculate a bit error rate.

> What I need to do is be able to determine the bit
> error rate when I am using two different cables. I need to be able to
> validate that cable a can transfer data as efficiently as cable b.  I have
> been trying to explore your software to decide if it will allow me those
> capabilities. What I did was capture some data (ctrl k or Capture - Start),
> although I'm not sure where this data is being captured from.

It's being captured from whatever network interface you specified when
you filled in the window popped up when you did control-K.

> Next, I
> clicked on Tools then Protocol Hiearchy Statistics. I copied a screen shot
> of what I am looking at. I am hoping you can help decipher this window. 
>  <<...OLE_Obj...>> 

Given that the screen shot was not attached to your mail, no, we can't.

> Under percent packets it lists 100%.  Does this mean that there was zero
> errors in data transfer?

No, it means that, for the protocols for which it lists 100% (the
"Protocol Hierarchy Statistics" window should show more than one item),
all the link-layer had that protocol.  For example, by definition 100%
of the link-layer will show "Frame" as a protocol, as that "protocol"
is defined to provide all the information that *all* link-layer frames
have (such as arrival time and length).  In an Ethernet capture I have,
100% of the packets will have Ethernet as the protoco.

> Also, does this only account for data that was received

Yes.